IBM Selectric III models were equipped with two different types of ribbons - the 1299095 SRS style, also used in Selectric II models and the 210 CRC "Bicycle" style on machines built between February 1982 through October 1984 (that's the official dates anyway). It was nicknamed "bicycle" since the outline of the ribbon cartridge looks like a bicycle. The 210 style was designed supposedly to address the complaints of users who got carbon on their fingers when changing the ribbon on earlier machines. The 210 style was designed in a "cassette" where the ribbon lift arms were part of the ribbon housing. The ribbon was already threaded through the lift arms and didn't require the user to touch the ribbon film during replacement. I'm sure IBM saw another advantage as it meant users had to buy this new design ribbon directly from IBM until the aftermarket could ramp up to produce them, which increased IBM's profits on supplies. The many third-party suppliers for the older style 1299095 ribbons for the Selectric II had cut into their supply market and my guess is IBM wanted to recapture some of that.
Because the 210 "Bicycle" ribbon was only used for about two and one half years on only two models, the Selectric III and the IBM Personal Typewriter, it never had the demand in the market that the more common 1299095 ribbon had. Offices didn't like them since they needed to stock additional ribbon part numbers and preferred to use the same ribbon for all their IBM Selectrics. It was confusing for office supply stores to determine which ribbon was needed since buyers didn't know the build date of their typewriters. Even IBM apparently agreed that it was better to only use one ribbon design as they switched back to the 1299095 ribbon in December 1984.
Today, it's growing harder to obtain the 210 "bicycle" ribbon and the prices for them have risen sharply. According to my sources, the 210 "bicycle" ribbon is out of production mainly because no company produces the plastic parts for the ribbon cartridge anymore due to lack of demand. There are still some NOS (new old stock) ribbons for sale, but once these are gone there likely won't be any more. In order have better availability in the future, a Selectric III or IBM Personal Typewriter can be converted to use the more common 1299095 SRS ribbon. Just replace the ribbon plate, ribbon guides and ribbon lift arm with the parts for the 1299095 SRS style. The Escapement Bracket is slightly different, but can be modified in situ if you don't want to replace it.
Here is a Selectric III that I just refurbished for a customer and I suggested converting the ribbon from the 210 style to the 1299095 SRS style to reduce his ribbon costs and improve ribbon availability in the future.
I still repair/refurbish Selectrics, but I've been so busy with customer machines that I haven't refurbished any for sale lately. Maybe once I retire from my day job I'll get back into rebuilding them for sale.
